Improvement in the manufacture of sugar of lead and acetic acid



strut 'tillira LEONARD 1D. GALE, Or'WAsHINe'rON, 'Disrnror or COLUMBIA,AND IsAAc M. GATTMAN, Or New YORK, N. Y.

Letters Patent No. 93,817, dated August 17 1869. l

IMPROVEMENT'IN THE MANtrIAcm'trR-e."'or*A SUGAR or LEAD AND Aenrrc ACID.

` The Scheduievreferred to in these Letters-Patent and ol' the' same4 Toall'whom 'it 'may conce/rn v Be it known that we., LEONARD D. GALE,'ofWashington, District of Columbia, and ISAAC M. GATTMAN, l

of the city, county, and State of New York, have invented new'and usefulImprovements in the Manufacture of Sugar of Lead, which we verilybelieve have not been known or used before; and we declare that thefollowing is aefull and accuratedescription of the same.,

reference being had to the annexed drawings which make part of thisspecification.

.Figure 1 represents a boiler, being v avertie-al view l of the woodenshell, upper head removed, to show an end view ofthe three hollow'coppersteam-cylinders within, B, the shell being marked A.

Figures 2 and 3 represent a vertical view' of a pair of eorrodiug-tubs,seven feetdiameter at bottom.v the cover removed and tub unfurnished. i

Figure 4 represents a vertical view of the copperevaporator D, in awooden shell or box.

Figure 5, a longitudinal vertical section, 1)1, and showingsteam-passage underxit. Figure (i,l a transverse vertical section, D2,of .the same.

Figure '8, a perspective view of the centrifugal pump I G, over a caseof drawers, G', for 'drying the sugar of lead.

i Figure 9, a top view of a'wooden crystallizer, H, made of three-inchplank, of white-wood, well bolted, twelve feet long, eighteen incheswide, land twelve inches deep.

Figure 1Q, a longitudinal vertical section, 1]',of the same. v

Figure l1, a transverse section of the saine.

Figure 12, a'sect-ional elevation of a-corroding-tub, containing arotary sprinkler. A f

Figure 413, separate view of one of the drying-d1jaw ers, with Openbottom.

Figure 14 represents a perspective view of a castin g-furnace.

Figure 15, a perspectiveeview of a water-tub, with iron eolande-r for.casting wire.

Figure 1 6, .a sectional elevation of the'iLon Jrinegarstill, withsteam-jacket and rotary'agitator, as found on sale.

Figure 17, a 'sectional elevation of the corrodingtub, containing anoverflow-pump, P, sometimes used in place of the sprinkler fo'riwettingdown the'lead.

Figure 18 represents the dgublemtpumpet-pipe E".

Fig. 1G shows the conueddiimbfithe still with the corroding-tub, hymeans of trumpgtfpipe E, or a perforate pipe, o5 or o, foracidifyingftlthe liquor in the corroding-tub. 1 r "W i' i Figure 7, avertical view of the centrifugal drainer FQ Figs. 4 and 16 show theconnection of the still with the evaporator, by means of pipe E, toIacidify .the liquor in the evapora-tingpan. t

The nature of our invention consists in several new and distinctfeatures, which, when combined together,

constitute a complete process of manufacture. x We propose tomanufacture sugar of leadfby the combined and simultaneous action ofconcentrated acetic-acid vapors and, atmospheric air on metallic lead;and

vOur improvements relate not only to the production of sugar of lead,but also to the produc-tion ol' pure and concentrated acetic acid,employed in its manufacture.

In the manufacture of sugar of lead, either-one or the otherof thefollowing processes has heretofore been employed:

' First. Protoxide of lead (litharge) was dissolved in whiskey, ormalt-vinegar, of a strength offrorn thirtytwo to forty grains ofbicarbonate of potashto the ounce of the vinegar, equal-to about four tofive per cent. of hydratedacetic acid. The solution thus obtained wasunder addition offresh vinegar, to prevent the formation of basic salt.In this process the cost oi evaporaproduction considerably.

Second. Whiskey, or malt-vinegar of the above strength, was put intoastill, and heated over a furnace or by steam. The weak vinegar-vaporspassing over were brought in contact with the protoxide of lead, placedin a convenient vessel over a perforated bottom. lhe vinegar-vaporsacting on the protoxide of lead, the weak solution of sugar ,of leadcollected at the bottoni, and was transferred into the evaporating-pansibrcondensation. The same objections are applicable to this mode oilprocedure as to that of No. 1, with the single exception that thesolution of sugar of lead, as obtained under No. 2, was more free fromcoloxingrnatter than that obtained under No. l. Third A series ofsuitable tubs was vplaced in a range, one above the other, and filledwith lead spangles or lead Jw'i're. Vinegar of the above-mentionedstrength was run into the upper tub, left for some time in contact withthe lead, then run oli` vinto the next, &c., until it reached to thelower tub. By this time the lead' in the upper tubs wasexposed to .theaction of the atmosphere for the purpose of oxidation, the liquor wasraised from the lowest to the -upper tub to makea second circuit, andwas then transferredtothe evaprator for condensation.

in .all'. t hese different modes of manufacture only evaporated, orboiled down to the poi ut of crystallization,

tion, and the unavoidable loss of vinegar, besides the` additional time,fuel, and labor, enhance the cost ol"VV the first crop would yield whitemerchantable crystals ot' sugar of lead, the mother-liquor retainingall'the coloring-matter originally contained in the vinegar, or absorbedduring the process of evaporation.

To bleach the liquor for the purpose of yielding white sugar of lead, itwas boiled up with ground animal-charcoal, (bone-black,) and filtered,by which process the carbonate of lime in the bone-black decomposed anequivalent proportion of the sugar of lead in the solution, therebyeffecting a considerable loss,'besides that lost by the absorbing natureof the bone-black itself.

"`1Wh cn the different liquors were evaporated to theciystallizing-point, they were drawn off into the crystallizing-pans,left in repose for twenty-four to thirtysix hours, the mother-liquorremoved, the pans raised `on end for the purpose of draining, and thecrystals placed on drying-boards in a room slightly heated, and,'whendry,` broken up and packed for market.

This mode of drying requires considerable room, and about a 'weeks time,when no loss from heat shall be sustained.

All the different difficulties, obstacles, and disadvantages, in theprocesses above described, we obviate by our new improvements, which wewill now describe, to enable others skilled in the art to use the same.

For the better exemplificaton of our process, we divide thespecification under the following headings:

I. The sugar-of-lead solution; 1I. The evaporation and crystallization;

llI. lhe draining and drying; and as our improvements relate to the useof whiskey and malt-vinegar, as well as to wood-vinegar, we willdescribe both modes of manufacture under these three. differentheadings.

I. The Sugar-of-Lead Solution.

le make the sugar-of-lead solution from the metallic lead. To preparethe metal for our purpose, we cast it either into spangles or wire, andplace it into a corroding-tnb, figs. 12 and 17, arranged in thefollowing way:

The bottom, inside, is seven feet in diameter; the staves three and ahalf feet high, made of three-inch plank, of white oak or white poplar,the former preferrcd.

The tub is, by means of two perforate bottoms, divided into threechambers, the lower, N, for the leadliquor, the middle one7 M, for themetallic lead, and the upper one, L, containing the rota-ry sprinklers,with feed-funnel, or, in place thereof, the overflowpump 1, fig. 17.

The tub is tightly covered with a well-fitting cover or lid, into whicha copper pipe, four inches wide, is fitted, E1, figs. 2 and 3, for theescape of the surplus steam, to be utilized either for the evaporationand concentration of the solution of sugar of lead, or for some otherpurpose, as will be shown hereafter.

The whiskey, or malt-vinegar, of from four to five per cent. of hydratedacetic acid, (equal to thirty-two to forty grains of bicarbonate ofpotash to the ounce,) is put into a still, fig. 1, heated by steam bymeans of three concentric hollow copper steam-cylinders B, capable ofsustaining a pressure of twenty pounds to the square inch, by which thevinegar-vapors are driven through the double trumpet-pipes En into thechamber ot' the corroding-tub. l

This double trumpet-pipe is best seen in fig. 18, E, and consists of twoconiccoppcr pipes, brazed together at their small ends.

The current of vinegar-vapors enters the/pipe in the direction ofthearrow. Small holes are made into this pipe, beyond its smallestdiameter, for the admission of atmospheric air.

The pipe has its induction-end in the still, fig. 1 or fig. 16, and theopposite, or eduction-end, enters the corroding-tub just below theperforate bottom.

By this arrangement atmospheric air rushes in through the small holes inthe pipe, simultaneously with the current of the acetic-acid vapors,whereby oxidation and acetification take place in one continuousoperation, and the metal is rapidly corroded and dissolved.

The solution of sugar of lead is continually falling, in drops orstreams, into the lower chamber of the corroding-tub. At the same time alarge surplus of heat is developed, partly from the chemical action ofthe acid and lead, and partly from the surplus heat of inch copper pipe,El, figs. 2 and 3, conducted from the upper chamber of the corrpding-tubinto the steamchamber of the evaporator, figs. 4, 5, and 6, toconcentrate the weak solution of the sugar of lead.

.To facilitate the corrosion of the metallic lead, it is necessary tokeepthe metal always clean, so as t0 offer a lbright surface to theaction of the atmospheric air and the acid-vapors.

We accomplish this in the most efficient and convenient way, by means ofthe rotary sprinkler, R, fig. 12, in connection with an endless belt orchain ofcopper buckets-a contrivance well known by its use inflouring-mills and grain-elevators, and therefore not necessary todescribe here.

The rotary sprinkler, made of copper, with f'unnel at the top, has onthe hollow vertical shaft two hollow horizontal arms, one on each sideof the central shaft, that on the right having a row of small holes inthe front, that on the left an equal number of holes on the rear; so,when the central shaft is supplied with will cause the machine torotaterapidly, and wash down the metal in the most perfect manner.

. The same purpose we accomplish by a lifting-pump, with equal overflowover the second perforate bottom, n', fig. 17.

But vinegar of the above-mentioned strength, of from ythirty-two toforty grains ot' saturation to the ounce, will only yield a very weaksolution of sugar ot' lead, which, for the purpose of crystallization,must be evaporated or condensed.

'lo save the additional expense of this operation and to gain time, wehave iliade an improvement in the distillation of such kind of vinegar,which enables us to produce a concentrated solution of sugar of leadwithout evaporation, which object we accomplish by the use of commonsalt, (chloride of sodium,) in the proportion of thirty-three pounds ofsalt to every one hundred pounds, or twelve gallons of the vinegar.

By the addition of the salt to the vinegar, the boiling-point of thelatter is raised several degrees' above the boiling-point of water orweak vinegar. The vinegar-vapors, as being more volatile, will thereforepass over below the boiling-point of the mixture of salt and vinegar,whereby more concentrated vapors of vinegar are brought in contact withthe metallic lead; hence a more concentrated solution of sugar of lead,obtained at once. l

The solution of salt, deprived of vinegar-vapors, may be evaporated todryness lby means ofthe surplus heat `out additional expense for itsrepeated use.

rlhe sugar.ot;-lead solution will always be in a basic state as long as`there is any lead in excess.

For the purpose of forming the marketable crystallized sugar ot' lead,the liquor must have an acid reaction on litmus paper, and for thisreason itis necessary to acidulate the liquor during evaporation, by theaddition of fresh vinegar, whereby a great portion of thevinegar-vapors, which surplus heat is, bythe four liquor from the lowerchamber of' the corroding-tub, the reaction of the liquid in thelrorizontal arms z z of the corrot'ling-tu'b, by pipe El, figs. 2 and 3,withv the vinegar is not only lost, but also coloring-matter from the vincgar is added to the' solution.

To remedy this' evil we have .contrived the following improyements: Whenthe lower space N, figs. 12 and 17, of the corroding-tub, is filled .upso high with the basic solution of the sugar of lead as to cover theopening ofthe trumpet-pipe E, the rotary sprinkler or pump is stopped,whereby the corrosion ofthe lead ceases. rlhe vinegar-vapors comingoverA from the still are condensed in the basic solution of sugar oflead, and the latter acidulated thereby, which will be tested by itsreaction 0n litmus papel'.

When the solution is brought to the acid state, it is immediatelytransferred into the crystallizing-pans; or the basic solutionmight befirst transferred-into the evaporator, and a branch-pipe, E, Figure 20,from the still, enters into the basic solution, wherein the acidvaporsare condensed, andthe solution acidified thereby 'free ofcoloring-matter.

Since the introduction of the revenue-tax' on distilled spirits andmalt-liquors,the use of whiskey or malt-vinegar in the manufacture ofsugar of lead is out of question. We were, therefore, compelled toresort to the use of pyroligneous acid, or wood-vinegar.

But here we had to meet with another difficulty.y

Pyroligneous acid, free from odor and coloringmatter, is not any cheaperthan malt or whiskey-vinegar, and when not-free from both, it cannot beused.

Perfectly colorless and odorless pyroligiieous acid has heretofore beenmade only by repeated distillations of the product of decomposition ofacetate of lime with hydrochloric acid or diluted sulphuric acid, bywhichprocess the cost of the pure acid becomes too high for itsapplication in the manufacture of sugar of lead.

By repeated .experiments we have inventeda new process for theproduction of pure acetic acid from the acetate of lime in oneoperation, by 'which process we are enabled to apply it profitably inthe manufacture of sugar of lead. 4

The nature of this improvement consists in decomposing dry acetate of.lime by concentrated sulphuric acid, of no less than 650 to 660 Baume,in an 'apparatus-provided with an agitator, by which the adhesion of theresulting sulphateof lime in course of operation is prevented, thevolatile oily matter of the lime-salt solidified, and the passing overof pure, colorless, vand `odorless acetic-acid gas etfectually secured.

An iron still, iig. 16, with steam-jacket for heating, and an agitatorfor stirring the contents, cylindric in form, and capable of workingiive hundred pounds of acetate of lime with convenience, ischargedwith-dry acetate of lime and concentrated sulphuric acid, of 660Baum, in the proportion of one hundred pounds of the former to sixtypounds of the latter, and theagitator set in motion.

. By the chemical reaction, enough heat is evolved to liberate overone-half of the acetic acid, in a pure state, without the application ofartificial heat. Only when the-'action begins to slacken, steam isgradually employed, and continued until the acid-vapors are all driven othrough the trumpet-pipe E into the corroding-tnb. 'lhe'flow ofsulphuiic acid is regulated by the funnel y, iig. 16.

In working the still, the heat from the'chemical action accumulates inthe first part of the process, while, in the latter part, git diminishesgreatly. To avoid the excess' of the former, we throw cold water intothe jacket and ply the agitator vigorously; and, to avoid the want ofheat in'the latter, we throw steam into the jacket. i

In all other respects the arrangements are the same as those in theapplication of whi'slrey or malt-vinegar.

II. Evaporztioaaiul Crystallization.

v y thepse of acetate of lime, a concentrated colorless solution ofsugar of lead is obtained, ready, without evaporation, to. be run oiiimmediately into the crystallizers.

lVhen malt or whiskey-vinegar is used, with the addition-of salt, orchloride of sodium, as'statedabove, the same result will bel obtained.But when whiskey or malt-vinegar is used, without salt, only aweaksolution of sugar of lead is the result, which must be evaporated orcondensed for the purpose of crystallization. This we accomplish by thesurplus heat of the corroding-tub, by the escape-pipe E1, figs. 2 and 3,without additional cost.

\ The evaporator consists of a wooden shell or box,

twelve inches deep, lined with copper.

The copper bottom of this pan rests on ten longitudinal bearing-strips,one and a half inch high, fastened to the bottom of the wooden shell orbox, forming a steam-chest:

The four-inch copper pipe El, leading from the upper chamber` of thecorroding-tub, enters the steam-box x, leading under 'the copper bottomof the evaporator, the condensed steam and water escaping through pipeE. This escape-pipe is to be vfrequently examined, to guard against 'thewaste of acetic-acid vapors, whereby a loss would be sustained.

The solution of sugar of lead, although clear and I colorless atv first,often assumes a darker hue during the process of evaporation, and mustbe clarified.

rllhis has heretofore been done by bone-black and filtration, whichprocess involves a loss, as stated above.

We therefore substitute, for the bone-black, the sulphuretted-hydrogenwater as decolorizing-agent, by mixing one pint of water, saturated withsulphurettedhydrogen gas, to every eighteen or twenty pounds'of sugar oflead held in solution, forming thereby a pref cipitate of sulphuret oflead, which is a most powerful agent of de'eolorizat-ion, and can beeasily reduced again into metallic lead, that noloss is sustained,although the quantity of sulphuret of lead is in itself insignifi-Acant, amounting only to about one'hundred and eighteen-grains for everyeighteen or twenty pounds of sugar of lead contained in the solution. l

The process of making sulphuretted-hydrogen water is so simple and wellknown by chemists, that we omit a description of the same. 4 Whentheliquor is suiiciently concentrated to the crystallizing-point, it istransferred into the crystallizers, figs. 9, 10, 11, and left until asufficient quantity o f crystals is formed, when the mother-liquor isrun off and the crystals are ready for III. Dmim'ng and Drying'. In'place of the old process of draining and'drying on shelves, in a veryslightly heated room, we have devised thefollowing plan:

frame,`containing a series of drawers, arranged veitically. The drawerslt the case very accurately on all the vertical sides, while the bottomsof the drawers are made of open canelwork, not unlike the cane-seats ofchairs, G2. An opening in the lowest portion ofthe drying-box admitsatmospheric air, while a rotary pimp or fan is connected with `the topof the case G, fig. 8, to exhaust continually the entire series ofdrawers, by which gs. 4, 5, 6, twenty-five feetV long, iv e feet wide,and- Weplace the damp crystals in a rotary vertical cyl- This drylng-boxG1, fig. 8, consists of a well-made I means the damp crystals are easilydeprived of moisture, and fitted for the market.

Having stated the nature of our invention, and the methods of using thesame,

XVhat we claim as our invention, and desire to secure by Letters Patent,is-

1. The manufacture of sugar of lead, by the process of corroding themetal by vapors of vinegar mixed with atmospheric air, substantially asdescribed` 2. Applying the surplus heat fromthe steam of vinegar, andthe chemical action of the acid on the lea-d, for concentrating thesolution of sugar of lead, and for other purposes.

3, Concentrating the vapors of malt or whiskeyvinegar by means of commonsalt, substantially as described. i

4. Bleaching the solutions of sugar of lead by means of sulphurettedhydrogen, substantially in-the manner herein set forth.

5. Acidifying the basic solution of sugar of lead, substantially in themanner herein described.

Draining and drying sugarof lead, by centrifugal action, substantiallyas described, as an improvement on the mode now used of drying onshelves.

7. The use of the double trumpet-blowing pipes, or their equivalent, formixing the vinegar-vapors with air, substantially as described.

8. XVashing down the corroded lend by means of the rotary sprinklers, ortheir equivalents, as herein set forth.

9. Generating acetic acid, free from pyroligneous odor and color, bysimple distillation of acetate oflime with sulphuric acid, substantiallyas herein described.

L. D. GALE.

ISAAC M. GATTMAN.

Witnesses:

A. E. GALE, C. A. GRM/Es.

